In drilling, downhole completion, production, transport, storage, and processing of crude oil and natural gas, including waste water associated with crude oil and gas production, and in the storage of residual fuel oil, H2S and/or mercaptans are often encountered. The presence of H2S and mercaptans is objectionable because they often react with other hydrocarbons or fuel system components. Another reason that the H2S and mercaptans are objectionable is that they are often highly corrosive. Still another reason that H2S and mercaptans are undesirable is that they have highly noxious odors. The odors resulting from H2S and mercaptans are detectable by the sense of smell at comparatively low concentrations and are well known. For example, mercaptans are used to odorize natural gas and used as a repellant by skunks and other animals.
The predominant H2S and mercaptan scavengers for natural gas and crude oil are monoethanolamine (MEA) and monomethylamine (MMA) triazines. The use of triazines to scavenge H2S and mercaptan scavengers is described in U.S. Pat. Nos. 5,347,004; 5,554,349; 5,958,352; and 6,663,841 assigned to Baker Hughes Incorporated, all of which are incorporated herein by reference.
The dialdehyde glyoxal (C2H2O2) and the aldehyde acrolein (C3H4O) have been used as H2S scavengers in these instances. Glyoxal may be corrosive to mild steel under some conditions. Acrolein is an extremely toxic substance which operators do not like to use.
It would be desirable if new H2S and/or mercaptan scavengers or new synergistic combinations of old H2S and mercaptan scavengers could be discovered which are very effective, but which overcomes the deficiencies of prior scavengers.